# How to compress a PDF

To compress a PDF, choose the file in the box below, pick Recommended or Smallest file and press Compress the PDF. The pictures inside are saved again at about 170 or 120 dpi, so a scanned PDF often ends up a fraction of its size, while text and page sizes stay as they were. It is free, with no account and no watermark.

## How to make a PDF smaller

1. **Choose the PDF.** One file of up to 50 MB and 300 pages.
2. **Pick the level.** Recommended keeps print sharp at about 170 dpi on an A4 page. Smallest file goes to about 120 dpi, still easy to read on screen.
3. **Press Compress the PDF.** A scan of a few pages takes a few seconds. The next screen shows the size before and after.
4. **Download the smaller PDF.** It has the same pages, in the same order and at the same page size.

Compressing reads no text, so it costs nothing to run and needs no account. One connection can compress 10 files an hour and 40 a day.

## What changes and what stays

- **Photos and scanned pages**: Saved again as JPEG at about 170 dpi, or 120 dpi with Smallest file
- **Text and vector drawings**: Unchanged, still sharp and selectable
- **Page size and page count**: Unchanged
- **Black and white scans**: Unchanged, they are already stored compactly
- **Pictures with transparency**: Unchanged, so logos and signatures keep their outline
- **Watermark**: None

When the compressor cannot make a file smaller, you get the original back and the result says so. That happens with PDFs exported from Word or a website, which hold text and little else.

## Why is my scanned PDF so large?

A scanner or a scanning app stores each page as a photo. At 300 dpi an A4 page is about 2,500 by 3,500 pixels, and saved at high quality that photo can weigh one to three MB on its own. Ten such pages and the PDF is too large to attach to an email or to upload to a form with a size cap.

Most readers never need 300 dpi. Text stays crisp on screen and in print at 150 to 200 dpi, so saving the pages again at that density removes weight nobody sees.

## Size limits you may be working against

A personal Gmail account sends attachments of up to 25 MB, and a larger attachment is turned into a Google Drive link instead[1]. Upload forms for applications, universities and employers set their own caps, often far lower. Check the number on the form, compress with Recommended first and switch to Smallest file only if the result is still too large.

## Other ways to compress a PDF

On a Mac, open the PDF in Preview, choose File, then Export, and pick Reduce File Size in the Quartz Filter menu[2]. Apple notes that the compressed PDF may be of lower quality than the original[2], and the filter has no level to choose. The compressor on this page runs in any browser, lets you choose between two levels and leaves text and drawings alone.

If the size comes from many separate photos, convert them with the [JPG to PDF converter](https://www.loreai.org/jpg-to-pdf), which already sizes each page to about 210 dpi. To join the smaller file with others, use [merge PDF](https://www.loreai.org/merge-pdf).

## Translate the compressed PDF

A scanned certificate, contract or transcript in another language is the kind of file that ends up too large. On the result screen, Translate this PDF opens it in the [LoreAI app](https://www.loreai.org/app), which reads the scan with OCR and returns an editable Word file in one of 105 languages, with tables, stamps and headings in their places. Your first document is free, up to 3 pages.

LoreAI is not a certified translation service. Where an office asks for a certified translation, a translator signs a statement for the Word file.

## Questions people ask

### Is this PDF compressor free?

Yes. There is no account, no charge and no watermark. One connection can compress 10 files an hour.

### Will compressing make my PDF blurry?

Recommended keeps pages at about 170 dpi, which prints sharply. Smallest file uses about 120 dpi, which reads well on screen. Text and drawings are not touched at either level.

### Why did my PDF not get smaller?

A PDF made of text, such as one exported from Word, has no photos to shrink. In that case you get the original back unchanged.

### Can I compress a password protected PDF?

No. Remove the password first, for example by printing the PDF to a new PDF, then compress the new file.

## Sources

1. [Gmail Help: Attachment size limits](https://support.google.com/mail/answer/6584?hl=en), accessed November 5, 2026
2. [Apple Support: Reduce the size of a PDF in Preview on Mac](https://support.apple.com/guide/preview/reduce-the-size-of-a-pdf-prvw1509/mac), accessed November 5, 2026

By Matt Mountain · Updated November 5, 2026